The Common house martin is a migratory bird that belongs to the swallow family. It feeds on insects that are caught in flight, and it migrates to climates where flying insects are plentiful. It has a blue head and upper parts, white rump, and pure white underparts, and is found in both open country and near human habitation.
Common house martins breed in Europe, North Africa, and across the Palearctic and winter in sub-Saharan Africa and tropical Asia. They prefer open country with low vegetation, such as pasture, meadows, and farmland, usually near water. They may also be found in mountains and near trees since they provide insect food and also roosting sites. On their wintering grounds, Common house martins use similar open habitats. In the tropical parts of their wintering range, like East Africa and Thailand, they occur mainly in the higher areas.
Common house martins are social birds. They spend most of their day flying for hours hunting their prey. Common house martins hunt at a height of 21 m (69 ft) during the breeding season, typically within 450 m (1,480 ft) of the nest. They will also follow the plough or large animals to catch disturbed insects. On the wintering grounds, they usually hunt at a greater height of over 50 m (160 ft). Common house martins are migrants which move on a broad-front, and they usually travel in daylight. They are noisy birds, especially at their breeding colonies. The male's song, given throughout the year, is a soft twitter of melodious chirps. The contact call is a hard 'chirrrp', and the alarm is a shrill 'tseep'.
Common house martins are monogamous forming strong pair bonds that remain together for life. Breeding birds return to Europe between April and May, and nest building starts between late March in North Africa and mid-June in Lapland. Common house martin nest in colonies. Both sexes build a closed cup nest from mud pellets under eaves or similar locations on buildings and line them with grasses, hair, or other soft materials. The female lays 4 or 5 white eggs and incubates them for 14-16 days. The newly hatched chicks are altricial (helpless), and after a further 22-32 days they leave the nest. The fledged young stay with, and are fed by, the parents for about a week after leaving the nest. Occasionally, first-year birds from the first brood will help parents in feeding the second brood.
The Common house martin is not threatened globally but its numbers may be reduced by poor weather, poisoning by agricultural pesticides, lack of mud for nest building, and competition for nest sites with House sparrows.
According to the IUCN Red List, the total population size of the Common house martin is 10,000,000-500,000,000 mature individuals. In Europe, the breeding population consists of 11,200,000-23,600,000 pairs, which equates to 22,400,000-47,200,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.